Method 'forEach' cannot be resolved in certain context

[huajiaoyu]

I was trying to resolve argument types for all method call expressions(MethodCallExpr.class) in a method(Main Function in TestForEach.java in this case). I guess the exception happend with the generic type in List<String>.

Stack trace

Method Call: forEach
[java.util.function.Consumer<? super java.lang.String>]
Method Call: println
java.lang.RuntimeException: Method 'forEach' cannot be resolved in context ls.forEach(s -> {
    System.out.println(s);
}) (line: 12) MethodCallExprContext{wrapped=ls.forEach(s -> {
    System.out.println(s);
})}. Parameter types: [ReferenceType{java.util.function.Consumer, typeParametersMap=TypeParametersMap{nameToValue={java.util.function.Consumer.T=WildcardUsage{type=SUPER, boundedType=ReferenceType{java.lang.String, typeParametersMap=TypeParametersMap{nameToValue={}}}}}}}]
	at com.github.javaparser.symbolsolver.javaparsermodel.JavaParserFacade.solveMethodAsUsage(JavaParserFacade.java:659)
	at com.github.javaparser.symbolsolver.javaparsermodel.contexts.LambdaExprContext.solveSymbolAsValue(LambdaExprContext.java:74)
	at com.github.javaparser.symbolsolver.javaparsermodel.declarations.JavaParserParameterDeclaration.getType(JavaParserParameterDeclaration.java:64)
	at com.github.javaparser.resolution.model.Value.from(Value.java:45)
	at com.github.javaparser.resolution.Context.solveSymbolAsValueInParentContext(Context.java:199)
	at com.github.javaparser.symbolsolver.javaparsermodel.contexts.MethodCallExprContext.solveSymbolAsValue(MethodCallExprContext.java:145)
	at com.github.javaparser.symbolsolver.resolution.SymbolSolver.solveSymbolAsValue(SymbolSolver.java:76)
	at com.github.javaparser.symbolsolver.resolution.SymbolSolver.solveSymbolAsValue(SymbolSolver.java:82)
	at com.github.javaparser.symbolsolver.javaparsermodel.TypeExtractor.visit(TypeExtractor.java:335)
	at com.github.javaparser.symbolsolver.javaparsermodel.TypeExtractor.visit(TypeExtractor.java:65)
	at com.github.javaparser.ast.expr.NameExpr.accept(NameExpr.java:81)
	at com.github.javaparser.symbolsolver.javaparsermodel.JavaParserFacade.getTypeConcrete(JavaParserFacade.java:501)
	at com.github.javaparser.symbolsolver.javaparsermodel.JavaParserFacade.getType(JavaParserFacade.java:349)
	at com.github.javaparser.symbolsolver.javaparsermodel.JavaParserFacade.getType(JavaParserFacade.java:331)
	at com.github.javaparser.symbolsolver.JavaSymbolSolver.calculateType(JavaSymbolSolver.java:294)
	at com.github.javaparser.ast.expr.Expression.calculateResolvedType(Expression.java:575)
	at cn.hjy.drawiogen.DrawioGenApplicationTests.lambda$getTypeStrListFromCallExpr$2(DrawioGenApplicationTests.java:83)
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
	at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:575)
	at java.base/java.util.stream.AbstractPipeline.evaluateToArrayNode(AbstractPipeline.java:260)
	at java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:616)
	at java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:622)
	at java.base/java.util.stream.ReferencePipeline.toList(ReferencePipeline.java:627)
	at cn.hjy.drawiogen.DrawioGenApplicationTests.getTypeStrListFromCallExpr(DrawioGenApplicationTests.java:89)
	at cn.hjy.drawiogen.DrawioGenApplicationTests.lambda$main$0(DrawioGenApplicationTests.java:66)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at cn.hjy.drawiogen.DrawioGenApplicationTests.lambda$main$1(DrawioGenApplicationTests.java:64)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at cn.hjy.drawiogen.DrawioGenApplicationTests.main(DrawioGenApplicationTests.java:61)

Main function

    public static void main(String[] args) {
        try {
            CombinedTypeSolver combinedTypeSolver = new CombinedTypeSolver(new ReflectionTypeSolver());
            TypeSolver javaParserTypeSolver = new JavaParserTypeSolver(new File("D:\\my-workspace\\demo\\src\\main\\java"));
            combinedTypeSolver.add(javaParserTypeSolver);


            ParserConfiguration config = StaticJavaParser.getParserConfiguration();
            config.setSymbolResolver(new JavaSymbolSolver(combinedTypeSolver));
            StaticJavaParser.setConfiguration(config);


            FileInputStream file = new FileInputStream("D:\\my-workspace\\demo\\src\\main\\java\\cn\\hjy\\TestForEach.java");

            CompilationUnit cu = StaticJavaParser.parse(file);

            cu.findAll(MethodDeclaration.class).forEach(method -> {
                System.out.println("Method Name: " + method.getNameAsString());

                method.findAll(MethodCallExpr.class).forEach(callExpr -> {
                    System.out.println("Method Call: " + callExpr.getNameAsString());
                    System.out.println(getTypeStrListFromCallExpr(callExpr));
                });

                System.out.println("----------------------------------");
            });

        } catch (FileNotFoundException e) {
            System.out.println("File not found");
        }
    }

    private static List<String> getTypeStrListFromCallExpr(MethodCallExpr callExpr) {
        NodeList<Expression> arguments = callExpr.getArguments();
        return arguments.stream().map(arg -> {
                    try {
                        return arg.calculateResolvedType().describe();
                    } catch (Exception e) {
                        e.printStackTrace();
                        throw new IllegalStateException("Failed to resolve arg: "+arg.toString());
                    }
                }
        ).toList();
    }

TestForEach.java

public class TestForEach {

    public static void main(String[] args) {
        List<String> ls = new ArrayList<>();
        ls.add("sss");
        ls.forEach(s->{
            System.out.println(s);
        });
    }

}

[jlerbsc]

There seems to be an inference problem when solving the foreach() method. I haven't been able to pinpoint the exact cause of this problem.

[huajiaoyu]

There seems to be an inference problem when solving the foreach() method. I haven't been able to pinpoint the exact cause of this problem.

Thank you for your reply. Can you explain more about "an inference problem"? What did you mean by that?

[jlerbsc]

The Iterable.foreach method is a generic method which takes a parameter which JP tries to determine in order to resolve the foreach method.

[jlerbsc]

I don't have a solution to this problem at the moment.

[jlerbsc]

To complete this issue i think this section describes the problem https://docs.oracle.com/javase/tutorial/java/generics/genTypeInference.html#target_types

[hardik6955]

I need solution this code.